I basically solved this problem, but I am unsure what the final equation actually means.
blocks on table http://img560.imageshack.us/img560/9804/83508925.jpg
Write an expression for solving the mass of block C if mass B moves to the right with an acceleration of $a$. Note that the coefficient of friction between the table and mass B is $\mu$ and assume the mass of the string and pulley are massless.
Hint: $m_C > m_A + m_B$
Not sure how to include my Free-Body Diagrams, but my final answer looks like
$m_C = \frac{1}{g-a}\left (a\left ( m_A + m_B \right ) + g \left ( m_A + \mu m_b \right ) \right )$
Here is my question what happens if $a \to g$? It certainly can't mean mass C will become infinite. How would that even work? I also thought it might mean that the string might break but wouldn't that mean all strings tied to any block accelerating at g would break?
Thanks